A dry sleeve can be cast or pressed into a new block or used to recondition cylinders. A flanged, dry sleeve has a flange to fit a recess in the block. A wet sleeve has an outer surface directly exposed to coolant.

Cylinder head combustion chambers are designed to help improve the swirl or turbulence of the air-fuel mixture, and prevent fuel droplets settling on the surfaces of the combustion chamber or cylinder walls.

Gaskets can be made of soft materials such as cork or rubber, or they can be made of soft alloys and metals. Most gaskets are made to be used only once. Oil seals must also be replaced when a component is overhauled.

An operating valve tends to rotate and keep seating in a new place. This helps keep its face and seat free of carbon, and reduce sticking in the valve guide. It also spreads heat around the valve seat.

Coil springs normally hold valves on their seats. Their coils are usually closer at the bottom than the top. Oil seals on valve stems or guides prevent too much oil passing into the combustion chamber.

Intake valves are usually larger than exhaust valves because pressure forcing charge into the cylinder is much lower than that forcing the exhaust gases out. Different engines use different valve combinations.

An overhead valve or pushrod system has the valves in the cylinder head and the camshaft in the block near the crankshaft. Many engines use hydraulic valve lifters to quieten the engine and eliminate valve clearance adjustments.

Valve overlap is the amount of time the intake and exhaust valves are both open at once. Less overlap produces a smooth idle and more slow speed torque. More valve overlap allows better engine breathing at high speeds.

The overhead camshaft is located in the cylinder head. Double overhead cam systems often use a bucket tappet. Some overhead cam engines use a hydraulic lash adjuster to eliminate need for valve clearance adjustment.

Timing belts and chains are used on overhead camshaft engines, because the camshaft is further from the crankshaft. Timing belts are quieter than chains but usually require regular tensioning and replacement.

Bearings support and protect rotating parts and let them turn freely. Bearings can be either plain, usually called bushes, slippers or shells, or they can be anti-friction with rolling balls or rollers.

The flywheel is mounted on the rear of the crankshaft. It links the crankshaft to the transmission, through the clutch. With manual transmission, the flywheel is very heavy, and its momentum helps smooth out engine operation.

The objective of this procedure is to show you how to safely perform a cylinder compression test. Make sure the compression tester will safely handle the compression of the engine you are testing. Diesel (CI) engines operate at much higher compression pressures than Gasoline (SI) engines.

The objective of this procedure is to show you how to check and compare engine idle speed with the manufacturer's specifications. Checking the idle speed can only be done with a tachometer, which measures the engine revolutions per minute (rpm).

The objective of this procedure is to show you how to retrieve, record and clear stored OBD I & II diagnostic trouble codes using a scan tool. Remember, when retrieving codes for an OBD I vehicle, clear the codes then start the vehicle and recheck for any codes that reset. When diagnosing and OBD II vehicle, do not clear the codes until the vehicle is repaired.

Cam belts are primarily used on overhead camshaft engines. Always follow manufacturer's recommendations regarding cam belt change intervals and replacement procedures. The objective of this procedure is to show you how to safely remove and replace a cam belt.

Many vehicles require the technician to manually adjust the tension on the belt. Other vehicles have an automatic spring tensioning system. Depending on the system used on the particular vehicle, you should always follow the manufacturer's service instructions. The objective of this procedure is to show you how to remove and replace an engine accessory drive belt.